Yellow Fever

Yellow Fever vaccination and a WHO recognized stamp in the yellow immunization booklet are required for travel to and from most of Africa, South and Central America. It is contraindicated for the pregnant and they must carry a certificate stating such contraindication if they travel to an endemic region. There is no Yellow Fever risk in this region. Vaccination for travelers is available. Ask the travel clinic nurse where you can receive it.

Dengue fever was first described in America in the late seventeen hundreds and was called “breakbone fever” because of severe muscle pain. It is transmitted by female mosquitoes that bite during the day. There are four different species of this virus and re-infection is thus common in endemic regions. This results in four different clinical presentations. Uncomplicated dengue fever acts similar to an attack of influenza and many other viral infections with muscle pains, fever and usually a mild rash. It lasts for about one week and slowly improves leaving the patient fatigued for some time. Diagnosis is usually clinical and can be supported by some simple blood tests. It is common among tourists and requires only rest and paracetamol for fever and muscle pains. Complications are uncommon.

Dengue hemorrhagic fever and shock syndrome is the feared form and not uncommon among local children who have several prior infections with different strains of the virus. Warning signs are high fever, shock, petechii (small spots of bleeding in the skin or into the GI track), a very low platelet count and evidence of loss of vascular volume (high hematocrit). It is largely an immunological phenomenon and needs to be cared for by an experienced physician. It is rare among non residents. Prevention is by avoidance of mosquito bites. There is no vaccine.

Is like a “first cousin” to dengue fever but caused by a completely different virus and also transmitted by Aedis mosquitos. It is a non fatal illness that presents almost with identical symptoms as dengue but often is followed by swollen joints that may continue to plague the patient for up to several month. Treatment is symptomatic using paracetamol and rst as well as nonsteroids anti-inflamatory agents such as Brufen, Naprosin etc. Diagnosis is clinical but specific laboratory tests are available in major medical centers. There has been a recent spread of this infection across Asia. It is also seen in Africa where the name, derived from swaheli, originated.

These two insect transmitted bacterial infections are a cousin of epidemic louse born typhus, the scourge of the last two world and Korean wars and prison camps. Scrub typhus is transmitted by mites that live on bushes and bite you as you walk by. They cause a prolonged severe fever, often with rash and a small non painful often ignored ulcer at the bite site. Diagnosis is by history of being possibly exposed, the finding of the often scabbed ulcer and some blood tests. This infection responds rapidly to common antibiotics. Murine typhus is very similar but flees from mice and rats are the transmitters. Prevention is by avoidance of contact. There is no vaccine.

These two insect transmitted bacterial infections are a cousin of epidemic louse born typhus, the scourge of the last two world and Korean wars and prison camps. Scrub typhus is transmitted by mites that live on bushes and bite you as you walk by. They cause a prolonged severe fever, often with rash and a small non painful often ignored ulcer at the bite site. Diagnosis is by history of being possibly exposed, the finding of the often scabbed ulcer and some blood tests. This infection responds rapidly to common antibiotics. Murine typhus is very similar but flees from mice and rats are the transmitters. Prevention is by avoidance of contact. There is no vaccine.

This mosquito born virus is present all across Asia and now also in parts of Australia and the Pacific Islands. It is mainly a disease of pigs who do not get significantly ill from it and where infection and immunity is virtually universal. Other mammals including life stock and birds can also act as amplifying hosts and are the reason why this disease is now spreading to Moslem, non pig breading countries. Humans are incidental hosts having been bitten by a mosquito that has fed on a pig or other host. It is likely that only one in hundreds of humans actually becomes significantly ill when infected and few of those get the feared encephalitis (brain inflammation). Unfortunately, this form is often fatal and if recovery has come about, significant sequele often remain. Prevention is again by avoiding mosquito bites and not spending time near pig farms. There are several vaccines against this disease. The most commonly used Biken vaccine is made from mouse brains and has a protective life of around 3 years. Better vaccines with good safety records and long duration of immunity are coming now out of China with the help of the Gates Foundation. Vaccination is recommended for tourists and expats who contemplate much rural travel in Asia.